Revert "[InstCombine] Try to fold trunc(shuffle(zext)) to just a shuffle (llvm#78636)"

This reverts commit 4d11f04.

This breaks some programs as mentioned in llvm#78636

Author: pranavk

llvm/lib/Transforms/InstCombine/InstCombineCasts.cpp

@@ -103,13 +103,6 @@ Value *InstCombinerImpl::EvaluateInDifferentType(Value *V, Type *Ty,
       }
     }
     break;
-  case Instruction::ShuffleVector: {
-    Value *Op0 = EvaluateInDifferentType(I->getOperand(0), Ty, isSigned);
-    Value *Op1 = EvaluateInDifferentType(I->getOperand(1), Ty, isSigned);
-    Res = new ShuffleVectorInst(Op0, Op1,
-                                cast<ShuffleVectorInst>(I)->getShuffleMask());
-    break;
-  }
   default:
     // TODO: Can handle more cases here.
     llvm_unreachable("Unreachable!");
@@ -370,9 +363,6 @@ static bool canEvaluateTruncated(Value *V, Type *Ty, InstCombinerImpl &IC,
           I->getOpcode() == Instruction::FPToSI);
     return Ty->getScalarSizeInBits() >= MinBitWidth;
   }
-  case Instruction::ShuffleVector:
-    return canEvaluateTruncated(I->getOperand(0), Ty, IC, CxtI) &&
-           canEvaluateTruncated(I->getOperand(1), Ty, IC, CxtI);
   default:
     // TODO: Can handle more cases here.
     break;

llvm/test/Transforms/InstCombine/logical-select-inseltpoison.ll

@@ -671,8 +671,11 @@ define <4 x i32> @computesignbits_through_shuffles(<4 x float> %x, <4 x float> %
 
 define <4 x i32> @computesignbits_through_two_input_shuffle(<4 x i32> %x, <4 x i32> %y, <4 x i1> %cond1, <4 x i1> %cond2) {
 ; CHECK-LABEL: @computesignbits_through_two_input_shuffle(
-; CHECK-NEXT:    [[COND:%.*]] = shufflevector <4 x i1> [[COND1:%.*]], <4 x i1> [[COND2:%.*]], <4 x i32> <i32 0, i32 2, i32 4, i32 6>
-; CHECK-NEXT:    [[SEL:%.*]] = select <4 x i1> [[COND]], <4 x i32> [[Y:%.*]], <4 x i32> [[X:%.*]]
+; CHECK-NEXT:    [[SEXT1:%.*]] = sext <4 x i1> [[COND1:%.*]] to <4 x i32>
+; CHECK-NEXT:    [[SEXT2:%.*]] = sext <4 x i1> [[COND2:%.*]] to <4 x i32>
+; CHECK-NEXT:    [[COND:%.*]] = shufflevector <4 x i32> [[SEXT1]], <4 x i32> [[SEXT2]], <4 x i32> <i32 0, i32 2, i32 4, i32 6>
+; CHECK-NEXT:    [[TMP1:%.*]] = trunc <4 x i32> [[COND]] to <4 x i1>
+; CHECK-NEXT:    [[SEL:%.*]] = select <4 x i1> [[TMP1]], <4 x i32> [[Y:%.*]], <4 x i32> [[X:%.*]]
 ; CHECK-NEXT:    ret <4 x i32> [[SEL]]
 ;
   %sext1 = sext <4 x i1> %cond1 to <4 x i32>

llvm/test/Transforms/InstCombine/logical-select.ll

@@ -707,8 +707,11 @@ define <4 x i32> @computesignbits_through_shuffles(<4 x float> %x, <4 x float> %
 
 define <4 x i32> @computesignbits_through_two_input_shuffle(<4 x i32> %x, <4 x i32> %y, <4 x i1> %cond1, <4 x i1> %cond2) {
 ; CHECK-LABEL: @computesignbits_through_two_input_shuffle(
-; CHECK-NEXT:    [[COND:%.*]] = shufflevector <4 x i1> [[COND1:%.*]], <4 x i1> [[COND2:%.*]], <4 x i32> <i32 0, i32 2, i32 4, i32 6>
-; CHECK-NEXT:    [[SEL:%.*]] = select <4 x i1> [[COND]], <4 x i32> [[Y:%.*]], <4 x i32> [[X:%.*]]
+; CHECK-NEXT:    [[SEXT1:%.*]] = sext <4 x i1> [[COND1:%.*]] to <4 x i32>
+; CHECK-NEXT:    [[SEXT2:%.*]] = sext <4 x i1> [[COND2:%.*]] to <4 x i32>
+; CHECK-NEXT:    [[COND:%.*]] = shufflevector <4 x i32> [[SEXT1]], <4 x i32> [[SEXT2]], <4 x i32> <i32 0, i32 2, i32 4, i32 6>
+; CHECK-NEXT:    [[TMP1:%.*]] = trunc <4 x i32> [[COND]] to <4 x i1>
+; CHECK-NEXT:    [[SEL:%.*]] = select <4 x i1> [[TMP1]], <4 x i32> [[Y:%.*]], <4 x i32> [[X:%.*]]
 ; CHECK-NEXT:    ret <4 x i32> [[SEL]]
 ;
   %sext1 = sext <4 x i1> %cond1 to <4 x i32>